Phosphoinositide signaling and sperm fertility

描述（由申请人提供）：哺乳动物精子以静止和不育状态储存在男性生殖道中。只有在雌性生殖道内的孵化过程中，才能成功地到达受精地点并与卵子相互作用。精子中导致这种功能成熟的分子变化统称为获能。这些过程对于繁殖是必不可少的。因此，能化的生理调节因子可能为避孕干预提供新的靶点。精子膜上的多磷酸化磷酸肌苷介导了获能和精子-卵子相互作用的关键步骤。然而，对调节这些磷酸肌苷水平的脂质激酶和磷酸酶知之甚少。在这里，我们关注的是3'-磷酸肌醇磷酸酶，Tpte。正如将讨论的，Tpte转录本仅在生精细胞中检测到，预期的酶活性表明在获能中起作用。此外，初步数据显示附睾尾小鼠精子在前头和鞭毛中含有酶活性Tpte蛋白。然而，由于缺乏试剂，我们没有关于这种蛋白质在精子中的作用的直接信息。在这项探索性研究中，我们将产生一个Tpte位点突变和缺乏磷酸酶活性的小鼠系，并检查这些小鼠的生殖表型。此外，我们将开始分析tpt磷酸酶的催化活性。这项探索性研究代表了确定Tpte以及其他磷酸肌苷激酶和磷酸酶在精子功能和生殖中的作用的长期努力的第一阶段。

DESCRIPTION (provided by applicant): Mammalian sperm are stored in the male reproductive tract in an immotile and infertile state. The ability to reach the site of fertilization and to interact with eggs successfully is only developed during incubation within the female reproductive tract. The molecular alterations in sperm that account for this functional maturation are, collectively, known as capacitation. These processes are essential for reproduction. As such, the physiological regulators of capacitation may provide novel targets for contraceptive intervention. Polyphosphorylated phosphoinositides in the sperm membrane mediate key steps in capacitation and sperm-egg interaction. However, little is known about the lipid kinases and phosphatases that regulate the levels of these phosphoinositides. Here, we focus on the 3'-phosphoinositide phosphatase, Tpte. As will be discussed, Tpte transcripts are detected only in spermatogenic cells and the anticipated enzymatic activity suggests a role in capacitation. In addition, preliminary data is presented showing that cauda epididymal mouse sperm contain enzymatically-active Tpte protein in the anterior head and in the flagellum. However, we have no direct information regarding the role of this protein in sperm due to a lack of reagents. In this exploratory study we will generate a mouse line in which the Tpte locus is mutated and lacking phosphatase activity, and examine the reproductive phenotype of these mice. In addition we will begin an analysis of the catalytic activity of Tpte phosphatase activity. This exploratory study represents the first stage of a long-term effort to determine the role of Tpte, as well as other phosphoinositide kinases and phosphatases, in sperm function and reproduction. PUBLIC HEALTH RELEVANCE: This project focuses on the control of sperm fertility. As such, it directly relates to two issues of health relevance. First, episodes of infertility affect 10-15% of couples in the US and this work may lead to new treatments for this condition. Second, population is now estimated to exceed 6,700 million world-wide. This project examines a sperm-specific lipid phosphatase that would provide a novel target for contraceptive intervention. The experiments carried out here will determine the role of this phosphatase in sperm fertility and begin characterization of phosphatase activity.